The statement, signed by spokesmen Zabihullah Mujahid and Qari Yusouf Ahmadi, called on supporters to "help write messages and letters on social media" to show a united front.

The Taliban confirmed the death of Mullah Omar, the reclusive leader who ruled Afghanistan from 1996-2001 and sheltered Osama bin Laden, after Afghanistan's security agency said he had died in April 2013.

His deputy, Mullah Akhtar Mansoor, was chosen to succeed him by the insurgent group's seven-member supreme council, but Mullah Omar's relatives rejected the decision, calling for a wider election and revealing a rift within the movement.

"We have tried our best to distribute materials through our official websites, Facebook, Twitters accounts, cellphone messages and other means, but enemy spies are constantly suspending and restricting our access," Tuesday's statement said.

"So help us in this regard by sharing and distributing all materials as widely as possible," it said.

The Afghan government, meanwhile, banned any public mourning for Mullah Omar, saying late Monday that it would cause "anguish and humiliation" for those who have lost loved ones to the war with the Taliban.

A statement from the National Directorate of Security said public gatherings to commemorate Mullah Omar's death would be a "legitimate military target."

The NDS statement described Mullah Omar's death as an "assassination," without providing further details. Agency spokesman Hassib Sediqi earlier said the manner of Mullah Omar's death in a Karachi hospital was "suspicious," without elaborating.